I'm researching fuel pump choices for my in -tank application.

Build target is 5-7psi, for about 500rwhp from a heads/cam LT1, T76, 60lb Dekas.

I was planning on using the Aeromotive 340 pump, but noticed a few folks leaving feedback on the Summit site that say they aren't lasting very well. Maybe because they didn't add the 10ga wire kit or something? If the pump runs slow due to low voltage, would that cause overheating? Is this a common known issue with the Aeromotive 340 ?

Anyhow, Holley has a couple options out there too.

There's this Accel, that seems it would work: (stated good to 650 forced induction)
https://www.holley.com/products/fuel...ps/parts/75169

And then there's the Holley branded version, says its a forced induction specific pump or the 255lph variety, but supposedly flows better at 80 than a "normal" 255 pump. Stated good to 750 @ 60psi forced induction
https://www.holley.com/products/fuel...s/parts/12-914

Anybody use either of those? They both cost more than the Aeromotive. Someone remarked that the Holley was made in USA, or at least enough to claim it.

I hate the thought of not using the factory wiring in the tank and the chassis. What's the best plan for install? Is there a pump out there that will do what I need and not require upgrading the wiring?

 

Walbro is the one company that knows how to make a reliable pump.

 

Sure I've heard of them. Thought I read too where folks had decided that weren't made as well as they used to be, and to steer clear. Forget where I saw it. Any truth to it?

Hate to rely on heresay, but hate to make a bad decision too.

On Walbro's site, 255lph high pressure, drop in deal. Made in USA, no mention of flow chart, HP rating etc.. ??
http://walbrofuelpumps.com/1987-1989...8cyl-5-7l.html

Looks like Racetronix offers a nice kit with the Walbro 255 HP pump and all the wiring for $150 or so on their site. Plug and play so it says. 600 or so FWHP, which should be about right for what I'm doing. That may be the ticket. It really seems like the most complete setup. I don't really want to hack the stock wiring all up if I don't have to.

Any other good options out there I'm missing?

 

The flow curve is on the website. http://walbrofuelpumps.com/walbro-gss-fuel-pumps

Flow rate increases as voltage increases. It also increases as regulated pressure decreases. If your fuel system operates at 40 psi (example only) then the pump will deliver somewhere between 60-70 gallons/hour depending how much voltage losses are present in your fuel pump wire harness. Then compare that fuel delivery rate to the amount of fuel your engine will need.

 

Also, you're turbocharged so you need to take into account the pressure of the air charge in the intake manifold because it reduces the real pressure across the fuel injector nozzle when the injectors deliver fuel. Net effect is it reduces flow rate.

 

I'm hoping the stock LT1 FPR will actually raise the fuel pressure at the rail due to boost acting on it, but good point. Website flow chart says 65 gph at 50 psi, and 13.5V, and 8.5A. 43.5 + 7psi boost is about 50. So 65 gph is also 296lph. A calculator i used reported a fuel requirement of 230lph at .6 BSFC. So based on that, the Walbro "should" work OK

Racetronix hints at 550RWHP or 600FWHP with their whole kit and stock lines. That about lines up with what I just saw.

 

mmmm.... not sure it works that way. Best if an experienced turbo user weighs in here.

I'd suspect the pump is seeing whatever the regulator is doing (43.5 psi) and that is what the pump flow rate is based on. The injectors are seeing 7 psi less across the the nozzle (36.5 psi) so that effects injector flow rate (and sizing) but not the pump flow rate.

I probably shouldn't even be replying here but it's midnight on a Friday and my wife is out of town and I'm bored. This is how bad advice happens.

 

With a vacuum referenced fuel pressure regulator, the regulator senses load. When that vacuum turns to boost, it'll raise the fuel pressure accordingly. That's where the upgraded fuel pump comes in, because the pressures rise, and throughput drops.

Works the same way that NOS uses nitrous pressure plumbed into the fuel pressure regulator to make the stock injectors flow the added fuel necessary on their 'dry' systems.

Of course all of the above assumes the fuel system has enough added capacity to handle the boost.

But anyway,

 

I had a supercharged LT1 Corvette back in the late 1990's with an FMU to raise fuel pressure. It worked okay (not great) but the consequences can be kind of nasty if the FMU fails.

 

For it to really work well, the pump has to be able to keep up, and the injectors need to sized to handle the boost, and the engine really needs to be tuned to understand what's going on. Never really looked into the old FMUs really. Always seemed to me like they were more of a workaround in the era of EFI black magic, witch doctory.

 

Yes, exactly. Car ran 121 mph trap speed with a stock tune in the ECM.

 

Cool, thanks. I was hoping the FPR would work with boost too.

 

Which is funny to me,because when we used to get old Arctic Cat Snowmobiles with Walbro carbs the first thing you did was heave the Walbro as far into the woods as you could and mount a round slide Mikuni in it's place.

 

Hello guys, I have just pulled my very first third gen pump and came across something I havent seen in any of the videos/how-to write ups so many members have done. Instead of a section of hose between the pump and fuel line there is an odd device. I purchased a generic (oem replacement) pump that did not include the afore mentioned hose and clamps. Should I just purchase a piece of fuel hose and clamps or should I to find a new whatever this thing is?








Tuned Performance posted a GM illustration some time ago that answers my question. The device is a "Fuel Pulse Dampener". I have been advised not to re-use this one as it quite likely has worn out, could be leaking, which would explain my fuel pump sounding like it was always on but not pressuring up. Thank you Tuned Performance

 

Have we talked about this?? Specifics on the build?

I have a '94 vette. And a spare LT1 on the stand waiting to be built into something cool.. And a dana44 and ZR6 in one of my garages..

-- Joe

 

You too? lol. Mikuni 34/36 ftw.

I switched to Doos..

-- Joe

 

A few things here:

-Don't look at a 255 for your setup. Look at a 340 or a 450. 7 PSI on an LT-1 with H/C will likely exceed 500 at the tire if all is set up well. Too much fuel is likely better than not enough in most cases.
-Wiring upgrade should be at the top of your list. With a typical pump you're likely talking 15 amps or more. See below chart and you'll get an idea. If you have 15 foot of 16ga (don't forget this runs all over the place) vs 10 ft of 10 ga wire you're talking over half a volt difference.
-If you have a base FP of 43 PSI and a stock LT1 regulator the flow will remain the same under boost if it's connected as stock. You'll increase 1 PSI of fuel pressure for every 1 PSI of boost. The exception to this is if your FP can't handle it, at which point flow will start dropping off.

 

I wouldnt count on that. I would definately look into a boost pressure refrenced FPR. My external walbro 255 has been good thus far, but i feel I'm at my limit with it. I would probably look towards a 340 atleast.

 

It was a car I had in the late '90s. Stock engine burned a piston so the owner had it rebuilt with JE forged pistons, and ported the heads and intake. Also had a half-mass flywheel, shorty headers, gutted cats. Those were the only engine mods.

It had a Vortech S-trim supercharger with a 9 psi pulley but actually made 12 psi after throwing away the restrictive Vortech intake and replacing with uniform diameter tubing. Had to cut the radiator shroud to fit the larger intake. There was an MSD timing retard dial in the cab. It ran circles around similar builds.

 

I'll figure on doing the wiring upgrade, either the Racetronic plug in deal, or wire up my own w/relay etc..

Is Aeromotive the one to consider for a 340 pump or still stick with Walbro and go to their 400lph?

Or back to my 1st post, the Accel or Holley unit seem to flow plenty, and fit the stock hanger in the tank. I just can't find much feedback on them.

What about these guys - Quantum Fuel Systems 340lph pump and a lifetime warranty? https://www.highflowfuel.com/i-28317...-5-7l-lt4.html

Would like to find something that fits in the stock location in the tank.

 

What about TRE performance
https://treperformance.com/i-873-che...1985-1998.html

 

Make sure you use submersible fuel line in place of the dampener. If you use regular EFI hose it won't last in the tank.

 

Almost all "fuel injection hose" is SAE 30R10 though, probably because the auto parts stores only want to sell one thing because their employees are idiots. But it's always good to check the labeling on the hose!

-- Joe

 

Aeromotive says they get 2000hours from 340 Stealth in-tank units
From aeromotive about pump life:

I am using Aeromotive 340 have in single turbo application @ ~550rwhp for around 8,000 miles

 

I've been running Aeromotive 340 pumps for 6 yrs or so. Most of that time has been E85 which if anything is harder on fuel pumps than regular gas. Haven't had any issues thus far. Also have plenty of friends with Walbro 255's (in tank) with no issues. When sizing a pump, don't forget about the option of running two pumps with the second coming on with an ECU output or even a simple hobbs switch. I am doing this with Aero 340's in on car and two Walbros in another. This has two benefits - for one, you have less amperage draw and fuel heating occurring when not under heavy load, and two - if you ever have an issue with one pump you can switch the other over as your primary pump and not be stranded somewhere. Obviously it takes a little more fab work in the tank but both of mine are homemade setups anyways. Although I will say fitting two 340's side by side through a third gen fuel tank hole is pretty tight!

 

I guess I'll add some feedback based on my results thus far.

What I ended up doing was buying a QFT 343 pump from Quantum fuel systems. About 80 bucks, quick ship via Amazon prime, and lifetime warranty.
Install went fine, had to solder and heat shrink the wiring connections, which caused me to question whether it would survive in fuel. So far it has. I've driven the car maybe 1000-2000 miles or so.

The rest of the fuel system is stock. Stock FPR on the stock LT-1 (93) fuel rail. 60lb Siemens injectors. Stock fuel lines on the car itself, stock style fuel filter, and used the 4th gen style lines and an adapter to get from fuel rail to the stock third gen lines in the engine bay.

Fuel pressure has been fine, right at 43 or so according to Harbor Freight gauge, motor running or not. Fuel pump wiring is also stock, going against the age old "requirement" of needing the hotwire type setup to increase wire size etc.. The pump is likely not pulling full load under almost all conditions, so perhaps it won't cause me any problems. I don't doubt that the hotwire kit is mucho better - much heavier wire etc.. I just wanted to see what happened without it.

Haven't ran more than 8 psi boost yet, it's a stock LT1 lower end, ported heads and mildish cam (224/224 @ .050). Haven't had any fuel delivery issues, running solid in 11.5 or so AFR, except for below. Not had it on the dyno yet, but I'd wager it's at least 450 at the tires. Still getting the tune lined out too. Kinda hard / risky when a third gear pull results in 135mph.

Only issue has been:
1) the stock fuel pump relay did seem to have an intermittent issue, not good on a boosted car. It would cough once in a while (wasn't sure what the problem was), then it left me stranded a couple times for a short period of time, then it finally quit, and was diagnosed and replaced and all was well for a while.
2) The fuel pump did seem to go out on me one day, at the house luckily. The pump simply would not run. I thought it was the relay again, but it was working OK. Double checked wiring connection at the rear seat area, and found +12V there. So figured the pump had went out. But upon pulling it out of the tank, the pump seems to run just fine. Couldn't find any smoking guns. But I decided not to take any chances, since pulling the tank yet again just wasn't sounding that fun. So I have installed a new QFT 343 pump in there instead. Not sure what I'm going to do with the old one. Quantum may warranty it, but probably not if it still spins with 12V on it. I haven't discussed this with them yet, so maybe they'd help me out, not sure. I hate the thought of the pump potentially leaving me stranded, but what can you do, besides as the post above suggests adding another pump in the tank for a backup. I'd love to see how that was done.

So anyway, I went total cheap skate on this project (on purpose) and it's seemed to work out pretty good, other than one questionable pump. The car is an animal, even with 2.73 gears.

Maybe this will help some other cheap sucker like me out there. Happy motoring!

 

Well I need to update yet again - the second new Quantum Fuel Systems pump seems to have left me stranded the other day. I had driven the car, stopped, restarted, etc, several times and it was fine. Then, at home in the garage later that day, she failed to start. Can hear the fuel pump relay clicking away but no sound from the pump. Even tried the manual fuel pump override wire to take the relay out the game, and still nothing. So I'm pissed, and just let it set for a while. Then, a couple days later (didn't touch anything), the fuel pump starts fine.

I think I'll give them a call tomorrow and see if they have any ideas. Never had this issue with the pump for the NA combo. I really don't think it's the wiring / relay. Even tried another relay, acts same way.

So at this point, I can't say I'd recommend the Quantum Fuel pump. Maybe there's something else going on, but it sure seems like another bad pump.

EDIT - Please read below thread for more info. It was actually the plastic connector on the underside of the sender assy. that was causing the intermittent problem. I soldered the wires to the pins and threw that connector away. Problem solved. It was never the pump.

Perhaps I'll start a new thread better suited to the discussion I need to have now.
<>other thread created here ><